Computer A: This computer has Outlook 2007 installed on an external hard drive, but the computer itself is not bootable.

Computer B: This computer has Outlook 2010 installed, and is bootable.

Desired outcome: Copy or export the tasks in Outlook 2007 which is installed on the external hard drive of the unbootable computer to Outlook 2010 installed on the bootable computer.

Shouldn't be too hard.

First, as you must know, the data that Outlook displays and manipulates are in one or more Personal Storage Tables, which are contained in files ending in .pst, e.g., Outlook.pst or MyStuff.pst. We shall use Outlook 2010 on the working computer to access the .pst file containing the tasks on the external hard disk.

Attach to the computer on which Outlook 2010 is installed the external hard drive containing the Outlook tasks you want to copy or export.

You can then select all the tasks in the old .pst file and drag them to the default Tasks folder in Outlook 2010.

Possible variations:

1) Copy the .pst file from the old system to the new system and then open it in Outlook 2010 rather than opening it in Outlook 2010 directly from the external hard disk.

2) Rather than move or copy the Tasks from the old Tasks folder to the new Tasks folder, import them. (I prefer moving or copying.)

Possible problem: If you're not sure which .pst file on the old system has the data you need, do a search on the external hard disk for all the .pst files and open all of them on the new system. You should then be able to see which file has the Tasks you need.

Great answer, but that's the first thing I did and it missed some tasks. In the end I had to make the 2007 drive bootable and mess around with outlook export. Still, +1 for very nice answer.
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AndrejaKoDec 13 '10 at 4:03